Case/power supply/power button issue

[Viltref]

So I have a really really really weird issue with my desktop. 

Whenever the computer goes into sleep mode, it just kinda turns off but then when I attempt to turn it on again I can. 

The power light flashes for a like 0.3 seconds, but then goes off. From here pressing the power button does nothing, to be able to turn on the pc I have to turn it off at the power supply, wait around 10 seconds then turn power supply back on and the computer can be used again. 

I have absolutely no idea why this is happening. 

 

I know it isn't a fault of the power supply not having a high enough wattage. (550W psu, i7 3770 over clocked to 3.9GHz, GT 640) and I am also sure that it isn't an issue with hibernation as sometimes when I haven't used the desktop in a while (say more than 3 days) it also won't turn on

 

 

This is my case -  http://www.coolermaster.com/case/mid-tower/elite-335u/

Motherboard - 

http://www.gigabyte.com/products/product-page.aspx?pid=4147#ov

I'll find the specific model of power supply when I get a chance. 

 

Any help would be greatly appreciated. 

[DolphinOps]

does it resume to the state it was when it shut off?

[Viltref]

On 25/02/2016 at 1:51 PM, DolphinOps said:

does it resume to the state it was when it shut off?

Sometimes it does, and sometimes it doesn't. 

[DolphinOps]

8 hours ago, Viltref said:

Sometimes it does, and sometimes it doesn't. 

Strange... can you test it with a different psu?

[Viltref]

On 04/03/2016 at 6:42 PM, DolphinOps said:

Strange... can you test it with a different psu?

Unfortunately not, since I don't have a spare one. 

[Crowes]

When you put it into sleep, have you ever tried shaking your mouse around to wake it up?

[Viltref]

On 10/03/2016 at 1:12 PM, Crowes said:

When you put it into sleep, have you ever tried shaking your mouse around to wake it up?

Moving the mouse doesn't work, but sometimes pressing buttons on keyboard or mouse does.

They definitely work when the desktop is put to sleep